The present invention relates to a process and apparatus for the preparation of cereal flakes.
The traditional manufacture of cereal flakes by extrusion comprises the following steps:
1) The mixture of cereal flours and other ingredients is introduced in the extruder-cooker. Under the combined effect of the temperature and pressure, the mixture becomes thermoplastic. PA0 2) The mixture is extruded through circular orifices where the dough undergoes an expansion caused by the sudden pressure drop and consequent vapourisation of the water, and a rotary knife cuts the dough into spherical grains about the size of a small pea. At this stage, the grains contain about 16% moisture. PA0 3) The grains are transported to two grinding rollers which flatten the grains to their well-known flake shape. PA0 4) The flakes may then optionally be sprinkled with an appropriate solution (flavours, sugars, salt, oil, water, gums, etc.) before roasting in an oven, e.g., gas, electric, in which the temperature diminishes progressively. The residual moisture content is from 1-3%. PA0 a) Stretching controls the density and preserves the flaky layered, crumbly texture of the strand. If a similar density is obtained by flaking, the texture becomes too hard and abrasive. PA0 b) The moisture content of the flakes immediately after formation is about half that of the traditional method and the drying can therefore be carried out in a reduced time.